nozzle

A nozzle is a device designed to control the direction and characteristics of a fluid flow as it exits or enters a system. By constricting the flow, a nozzle converts pressure energy into kinetic energy, typically increasing exit velocity and often reducing static pressure. Nozzles can also shape the jet, alter spray patterns, or influence turbulence and mixing. In compressible flows, the flow can become sonic at a throat, and further expansion occurs in a divergent section.

Nozzles are used in a wide range of applications. In propulsion, rocket and jet engines use de Laval nozzles to accelerate exhaust to high velocities. In consumer and industrial settings, spray and atomizing nozzles produce fine droplets or jet streams for agriculture, cooling, cleaning, painting, or firefighting. Fuel-injection systems use precise nozzles to meter and atomize fuel. Garden hoses and pressure washers use adjustable nozzles to vary spray distance and pattern.

Common types include converging nozzles for subsonic flows, converging–diverging or de Laval nozzles for high-speed jets, spray nozzles that create flat, conical, or broken patterns, and specialty nozzles for atomization, cooling, or combustion. The choice depends on fluid properties, desired velocity, pressure ratio, and the required spray or jet characteristics.

Design considerations cover material resistance to erosion and corrosion, wear from abrasives, temperature limits, and potential for clogging. Precision nozzles require tight manufacturing tolerances and calibration. Efficiency is influenced by losses due to friction and nonuniform flow at the inlet.